Laserfiche WebLink
Pitch Reclamation Project Colorado Mined Land Reclamation Board — 2016 Annual Reclamation Report <br /> 4.5 Rock Dumps <br /> 4.5.1 2015 Indian Rock Dump Piezometer Completion <br /> Four new piezometers (RD-01, RD-02, RD-03, and RD-04)were installed near the toe of the Indian Rock <br /> Dump to enable water level and water quality measurements within the shallow groundwater near the toe <br /> of the Indian Rock Dump, as well as to provide injection and/or monitoring locations for injection of <br /> phosphate reagents to facilitate establishing the Lowest Practical Level for uranium. The piezometer <br /> locations are illustrated in Figure 9. <br /> Well construction logs are provided on the CD attached to this report. The piezometers were designed in <br /> accordance with Colorado Office of the State Engineer Rules for Water Well Construction Rule 14 <br /> "Minimum Construction Standards for Monitoring and Observation Wells/Holes and Test Holes". A <br /> Colorado licensed well driller(Cascade Drilling LP)advanced the boreholes and conducted well installation <br /> and development. HMC completed minor drilling pad set up and road access grading prior to drilling as <br /> summarized in the TR-7 supporting information. Each borehole was advanced using a Gus Pech GP 24 <br /> truck mounted rotary sonic drilling rig that advanced an 8-inch diameter drive casing to total depth. <br /> Continuous core was retrieved and logged using standard geologic logging techniques. Boreholes were <br /> advanced through alluvium into native bedrock. The geology observed with boreholes consisted largely of <br /> sandy clays and gravel sediments that represent fill material placed during construction of the Indian Rock <br /> Dump, native alluvial sediments, and former soil horizons. In RD-02, the eastern-most borehole, a <br /> pegmatite boulder was encountered during drilling at a depth between 4 and 8 ft below ground surface <br /> (bgs). Leadville Dolomite bedrock was encountered near the total depth of each borehole, between 33 and <br /> 39 ft bgs in the piezometers. <br /> The piezometers were completed with the same design for each, which consisted of schedule 40 polyvinyl <br /> chloride(PVC) screen and riser casing. Screens were 20 ft long and consisted of 0.020 standard machine <br /> slot screen.An 8/16 size sand pack was placed around the screens to a depth approximately two ft above <br /> the top of the screen in each piezometer.Above the sand, a minimum of 2 ft of hydrated bentonite 3/8-inch <br /> chip was placed in the annulus to seal the screens,which were then grouted to the ground surface using a <br /> 5-percent bentonite cement grout mix. The piezometers were completed with a minimum of 3 ft of stick-up <br /> above the ground surface. A locking, capped steel surface vault was placed over the 4-inch riser casing. <br /> The 4-inch riser casing in each piezometer was topped with a sealing locking cap.A concrete 4-foot square <br /> apron was completed around surface vaults to allow for positive drainage away from each piezometer. The <br /> aprons were fitted with an aluminum cap to serve as a measuring point for surveys and water level <br /> measurements. <br /> The drillers set-up at the RD-03 location is shown in Photograph 22. The completed RD-03 piezometer is <br /> shown in Photographs 23 and 24. The completed piezometers are shown in Photograph 25. The well- <br /> established vegetation on the Indian Rock Dump is also highlighted in Photograph 25. <br /> 24 <br />